October 1, 2012

Initial observations on battery running and operations


With a total of about two hours stick time on the S-Cab I have the following observations. So far the battery system is 99 percent of what I expected. The only glitch I noted so far is if I run a heavy train and it stalls on the grade  (I have some very slight grades on the layout just to keep my engineers on their toes). I have to reset the throttle speed to zero and then give it the "gas" to get it moving.

Aesthetically, the battery and power supply circuit fill up the front half of the tender top, so the loco has to have a very full load of wood to hide it. In SMR's new locos, there should be room inside  the tender to hide the whole set-up, as the new locos have boiler drives. 

The video I posted last time shows the wood pile before I reversed the battery and Battery Power Supply (BPS) circuit position. At first I put the BPS below the battery as it fit in the opening in the tender roof. I hoped that by having the circuit sit partially in the opening it would create a slightly lower profile over all. But the battery on top made access to the magnetic on-switch on the BPS harder. So I redid the set-up by putting the battery below the BPS. I used two sided tape to hold the parts together. Then I rebuilt the wood pile using a section of the original SMR wood pile for the front, and a small tetrahedron box out of  1/32nd plywood to fit over the electronics. I painted the box black and then glued split wood logs to it. I left an opening for the off switch to be accessible. I kept the off switch loosely mounted  in case I need to swap out batteries in the future. I use a brakeman figure to disguise the switch.

Up to now my focus has been on building the layout. As my visitors and I have been operating it more we are starting to learn some lessons about running O scale ACW trains with link and pin couplers. Here they are for those considering O scale.

First and foremost is to avoid sharp curves in the design. While the locos can negotiate curves as sharp as 28 inches or even less, the curve drag will slow the train and stall a heavy train. If I ever get to redo this layout I will keep my curve radius as broad as possible, striving for 36 inch radius or more if possible.

Second, when backing a train, the best results occur when the coupler faces can push directly on each other. There must be no pressure on the link.

This means the links have to slide into the coupler as the car push against each other. When backing up using long links with the couplers equipped with internal backing plates, the link will strike the internal backing plates, and then yaw right and left. This causes the link to contact the edge of the coupler face opening and jam as the couplers offset relative to each other. The jamming action then causes the whole car to lift. Shorter links help reduce this jamming action. But shorter links are harder to manipulate when coupling.

I should note that the couplers I am using are my own design and are photo-etched. The SMR couplers are cast as one unit and one cannot remove the internal backing plate on those. I only have one set of those, plus the ones on the locos.

When I remove the internal backing plate, the link can slide totally into the coupler box. Then the two cars can push directly on their coupler faces. That allows the two coupler faces to slide laterally which neutralizes the lurching (to use John Allen's term for this phenomena.) The links provide no force on the coupler in this configuration. They are just along for the ride. I believe this is how the prototype couplers work too.

The links jam because I have 30 and 28 inch radii on my layout. This is equivalent to 15 and 14 inch radii in HO. That is really very tight. I also used number 5 turnouts. To make matters worse, I have a few spots where I created "Ess" curves as the diverging route leaves a turnout, especially on curved turnouts.

I must say I am pleased with how readily my visitors have taken to using the links and pins. No one has suggested I do away with them.


The working brakes are proving to be a maintenance problem. They need constant fiddling to keep working. The brake chains also are fragile and several have broken. I am reconsidering if I want to continue to add working brakes as I build up the rest of the cars.

Here and there the rails mysteriously go in and out of gauge. It must be a function of the wood ties and wet scenery application. Hopefully, once the main wet scenery is done, the track gauge will settle down and be consistent.

My Easy DCC system must be getting worried with my recent attention running the battery unit. I decided to fire up McCallum to move it to a different spot and it worked flawlessly. So I decided to take it on a spin around the layout. It worked great. It must know that it is on probation and is on its best behavior.







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